package com.hzdp.netty.http;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelProgressiveFuture;
import io.netty.channel.ChannelProgressiveFutureListener;
import io.netty.channel.SimpleChannelInboundHandler;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.DefaultHttpResponse;
import io.netty.handler.codec.http.FullHttpRequest;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpHeaderNames;
import io.netty.handler.codec.http.HttpHeaderUtil;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpResponse;
import io.netty.handler.codec.http.HttpResponseStatus;
import io.netty.handler.codec.http.HttpVersion;
import io.netty.handler.codec.http.LastHttpContent;
import io.netty.handler.stream.ChunkedFile;
import io.netty.util.CharsetUtil;

import java.io.File;
import java.io.RandomAccessFile;
import java.io.UnsupportedEncodingException;
import java.net.URLDecoder;
import java.util.regex.Pattern;

import javax.activation.MimetypesFileTypeMap;

public class HttpFileServerHandler extends SimpleChannelInboundHandler<FullHttpRequest> {

	private final String url;

	public HttpFileServerHandler(String url) {
		this.url = url;
	}

	@Override
	public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
		cause.printStackTrace();
		if (ctx.channel().isActive()) {
			sendError(ctx, HttpResponseStatus.INTERNAL_SERVER_ERROR);
		}
	}

	@Override
	protected void messageReceived(ChannelHandlerContext ctx, FullHttpRequest request) throws Exception {
		if (!request.decoderResult().isSuccess()) {
			sendError(ctx, HttpResponseStatus.BAD_REQUEST);
			return;
		}
		if (!HttpMethod.GET.equals(request.method())) {
			sendError(ctx, HttpResponseStatus.METHOD_NOT_ALLOWED);
			return;
		}
		String uri = request.uri();
		String path = sanitize(uri);
		if (path == null) {
			sendError(ctx, HttpResponseStatus.FORBIDDEN);
		}
		File file = new File(path);
		if (file.isHidden() || !file.exists()) {
			sendError(ctx, HttpResponseStatus.NOT_FOUND);
		}
		if (file.isDirectory()) {
			if (uri.endsWith("/")) {
				sendListing(ctx, file);
			} else {
				sendRedirect(ctx, uri + '/');
			}
			return;
		}
		if (!file.isFile()) {
			sendError(ctx, HttpResponseStatus.FORBIDDEN);
			return;
		}

		RandomAccessFile randomAccessFile = null;
		try {
			randomAccessFile = new RandomAccessFile(file, "r");
		} catch (Exception e) {
			sendError(ctx, HttpResponseStatus.NOT_FOUND);
			return;
		}

		long fileLength = randomAccessFile.length();
		HttpResponse response = new DefaultHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
		setContentLength(response, fileLength);
		setContentTypeHeader(response, file);
		if (isKeepAlive(request)) {
			response.headers().set(HttpHeaderNames.CONNECTION, "keep-alive");
		}
		ctx.write(response);
		ChannelFuture sendFileFuture = ctx.write(new ChunkedFile(randomAccessFile, 0, fileLength, 8192), ctx.newProgressivePromise());
		sendFileFuture.addListener(new ChannelProgressiveFutureListener() {
			@Override
			public void operationComplete(ChannelProgressiveFuture future) throws Exception {
				System.out.println("Transfer completed.");
			}

			@Override
			public void operationProgressed(ChannelProgressiveFuture future, long progress, long total) throws Exception {
				if (total < 0) {
					System.err.println("Transfer progress:" + progress);
				} else {
					System.err.println("Transfer progress:" + progress + "/" + total);
				}
			}
		});

		ChannelFuture lastContentFuture = ctx.writeAndFlush(LastHttpContent.EMPTY_LAST_CONTENT);
		if (!isKeepAlive(request)) {
			lastContentFuture.addListener(ChannelFutureListener.CLOSE);
		}
	}

	private static final Pattern INSECURE_URI = Pattern.compile(".*[<>&\"].*");
	private static final Pattern ALLOWED_FILE_NAME = Pattern.compile("[A-Za-z0-9][-_A-Za-z0-9\\.]*");

	private boolean isKeepAlive(FullHttpRequest request) {
		return HttpHeaderUtil.isKeepAlive(request);
	}

	private void setContentLength(HttpResponse response, long fileLength) {
		HttpHeaderUtil.setContentLength(response, fileLength);
	}

	private void sendRedirect(ChannelHandlerContext ctx, String newUri) {
		FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.FOUND);
		response.headers().set(HttpHeaderNames.LOCATION, newUri);
		ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
	}

	private void sendListing(ChannelHandlerContext ctx, File dir) {
		FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, HttpResponseStatus.OK);
		response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/html;charset=UTF-8");
		StringBuffer buf = new StringBuffer();
		String dirPath = dir.getPath();
		buf.append("<!DOCTYPE html>\r\n");
		buf.append("<html><head><title>");
		buf.append(dirPath);
		buf.append("目录:");
		buf.append("</title></head><body>\r\n");
		buf.append("<h3>").append(dirPath).append(" 目录 ").append("</h3>\r\n<ul>");
		for (File file : dir.listFiles()) {
			if (file.isHidden() || !file.canRead()) {
				continue;
			}
			String name = file.getName();
			if (!ALLOWED_FILE_NAME.matcher(name).matches()) {
				continue;
			}
			buf.append("<li><a href=\"").append(name).append("\">").append(name).append("</a></li>");
		}
		buf.append("</ul></body></html>");
		ByteBuf buffer = Unpooled.copiedBuffer(buf, CharsetUtil.UTF_8);
		response.content().writeBytes(buffer);
		buffer.release();
		ctx.writeAndFlush(response).addListener(ChannelFutureListener.CLOSE);
	}

	private String sanitize(String uri) {
		try {
			uri = URLDecoder.decode(uri, "UTF-8");
		} catch (UnsupportedEncodingException e) {
			e.printStackTrace();
		}

		if (!uri.startsWith(url)) {
			return null;
		}

		if (!uri.startsWith("/")) {
			return null;
		}

		uri = uri.replace('/', File.separatorChar);
		if (uri.contains(File.separator + '.') || uri.contains('.' + File.separator) || uri.startsWith(".") || uri.endsWith(".")
				|| INSECURE_URI.matcher(uri).matches()) {
			return null;
		}
		return System.getProperty("user.dir") + File.separator + uri;
	}

	private static void sendError(ChannelHandlerContext ctx, HttpResponseStatus status) {
		FullHttpResponse response = new DefaultFullHttpResponse(HttpVersion.HTTP_1_1, status, Unpooled.copiedBuffer("FAILED:" + status.toString() + "\r\n",
				CharsetUtil.UTF_8));
		response.headers().set(HttpHeaderNames.CONTENT_TYPE, "text/plain; charset=UTF-8");
	}

	private static void setContentTypeHeader(HttpResponse response, File file) {
		MimetypesFileTypeMap mimetypesFileTypeMap = new MimetypesFileTypeMap();
		response.headers().set(HttpHeaderNames.CONTENT_TYPE, mimetypesFileTypeMap.getContentType(file));
	}

}
